As a color correction scheme for improving the color reproduction effect in a color reproduction process of a printer and printing press, a method of converting data of an input color space into data of an output color space by a color masking method that obtains data of the output color space via matrix operations of data of the input color space and a lookup table (LUT) called a profile is prevalently used.
However, the output characteristics of a color printer and printing press show strong nonlinearity. Therefore, a global method such as a color masking method, i.e., a color correction method in which a change in matrix element influences the entire output color space, cannot sufficiently approximate the characteristics of the color printer and printing press in all color ranges. Even when a profile is provided, its table is often obtained by the color masking method, and color reproduction remains difficult.
To solve this problem, a method for providing a profile which can precisely approximate strong nonlinear output characteristics of a color printer and printing press, and allows precise color reproduction has been proposed.
Upon generating a profile, the colors of color patches of a sample image printed by a color printer or printing press are measured by a calorimeter. Upon colorimetry, calibration is periodically done to suppress colorimetric errors.